Cameras using a solid state image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) image sensor have been rapidly distributed.
In order to improve a resolution of a camera, a degree of pixel integration of a solid state image sensor has to be increased. Also, as cameras have become smaller and lighter due to the improvement of performance of lens optics built into them, and thus, cameras are being widely integrated into various mobile devices.
In lens optics included in such cameras, when the number of lenses increases, a desired performance may be obtained; however, increasing the number of lenses is not suitable for small and light cameras with lower costs. Thus, a design is necessary that is suitable for obtaining the desired performance of small and light cameras.
In such a lens design, a method of realizing a fixed focus lens system by using two to four lenses is being widely used, and a structure of an individual lens is determined in consideration of merits in each case, and specification of a desired performance. For example, if two lenses are used, aberration may not be sufficiently corrected in accordance that a size of pixel is reduced. If four lenses are used, the aberration may be sufficiently corrected, but the total length of the lens system is increased.
Therefore, various designs for meeting desired performance specifications such as a focal length, a viewing angle, and aberration correction by using a small number of lenses, that is, two to four lenses, are being suggested.